6029781984
Highlight the performance advantages of calling `string.split` with a block, instead of `string.split.each` with the same block. Includes other minor formatting corrections.
100 lines
3.3 KiB
Plaintext
100 lines
3.3 KiB
Plaintext
Returns an array of substrings of +self+
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that are the result of splitting +self+
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at each occurrence of the given field separator +field_sep+.
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When +field_sep+ is <tt>$;</tt>:
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- If <tt>$;</tt> is +nil+ (its default value),
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the split occurs just as if +field_sep+ were given as a space character
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(see below).
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- If <tt>$;</tt> is a string,
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the split occurs just as if +field_sep+ were given as that string
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(see below).
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When +field_sep+ is <tt>' '</tt> and +limit+ is +0+ (its default value),
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the split occurs at each sequence of whitespace:
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'abc def ghi'.split(' ') # => ["abc", "def", "ghi"]
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"abc \n\tdef\t\n ghi".split(' ') # => ["abc", "def", "ghi"]
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'abc def ghi'.split(' ') # => ["abc", "def", "ghi"]
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''.split(' ') # => []
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When +field_sep+ is a string different from <tt>' '</tt>
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and +limit+ is +0+,
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the split occurs at each occurrence of +field_sep+;
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trailing empty substrings are not returned:
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'abracadabra'.split('ab') # => ["", "racad", "ra"]
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'aaabcdaaa'.split('a') # => ["", "", "", "bcd"]
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''.split('a') # => []
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'3.14159'.split('1') # => ["3.", "4", "59"]
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'!@#$%^$&*($)_+'.split('$') # => ["!@#", "%^", "&*(", ")_+"]
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'тест'.split('т') # => ["", "ес"]
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'こんにちは'.split('に') # => ["こん", "ちは"]
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When +field_sep+ is a Regexp and +limit+ is +0+,
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the split occurs at each occurrence of a match;
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trailing empty substrings are not returned:
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'abracadabra'.split(/ab/) # => ["", "racad", "ra"]
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'aaabcdaaa'.split(/a/) # => ["", "", "", "bcd"]
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'aaabcdaaa'.split(//) # => ["a", "a", "a", "b", "c", "d", "a", "a", "a"]
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'1 + 1 == 2'.split(/\W+/) # => ["1", "1", "2"]
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If the \Regexp contains groups, their matches are also included
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in the returned array:
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'1:2:3'.split(/(:)()()/, 2) # => ["1", ":", "", "", "2:3"]
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As seen above, if +limit+ is +0+,
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trailing empty substrings are not returned:
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'aaabcdaaa'.split('a') # => ["", "", "", "bcd"]
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If +limit+ is positive integer +n+, no more than <tt>n - 1-</tt>
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splits occur, so that at most +n+ substrings are returned,
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and trailing empty substrings are included:
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'aaabcdaaa'.split('a', 1) # => ["aaabcdaaa"]
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'aaabcdaaa'.split('a', 2) # => ["", "aabcdaaa"]
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'aaabcdaaa'.split('a', 5) # => ["", "", "", "bcd", "aa"]
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'aaabcdaaa'.split('a', 7) # => ["", "", "", "bcd", "", "", ""]
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'aaabcdaaa'.split('a', 8) # => ["", "", "", "bcd", "", "", ""]
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Note that if +field_sep+ is a \Regexp containing groups,
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their matches are in the returned array, but do not count toward the limit.
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If +limit+ is negative, it behaves the same as if +limit+ was zero,
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meaning that there is no limit,
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and trailing empty substrings are included:
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'aaabcdaaa'.split('a', -1) # => ["", "", "", "bcd", "", "", ""]
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If a block is given, it is called with each substring and returns +self+:
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'abc def ghi'.split(' ') {|substring| p substring }
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Output:
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"abc"
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"def"
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"ghi"
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=> "abc def ghi"
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Note that the above example is functionally the same as calling +#each+ after
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+#split+ and giving the same block. However, the above example has better
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performance because it avoids the creation of an intermediate array. Also,
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note the different return values.
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'abc def ghi'.split(' ').each {|substring| p substring }
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Output:
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"abc"
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"def"
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"ghi"
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=> ["abc", "def", "ghi"]
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Related: String#partition, String#rpartition.
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